Crowder would start for the Hawks.
Crowder would start for the Bulls.
Bradley would start for the Cavs.
Bradley would start for the Mavericks.
Amir would start for the Mavericks.
David Lee very recently did start for the Warriors.
Amir would start for the Rockets.
Amir would start for the Pacers.
Crowder would start for the Clippers.
Crowder would start for the Grizzlies.
Thomas would start for the Bucks.
Crowder would start for the Pelicans.
Olynyk would start for the Pelicans.
Amir would start for the Pelicans.
Bradley would start for the Thunder.
Sullinger would start for the Raptors.
Lee would start for the Raptors.
Smart would start for the Jazz.
Bradley would start for the Jazz.
Sullinger would start for the Wizards.
Lee would start for the Wizards.
I think you can make a case for a number of your selections.
To put it simply, Smart, Bradley, Amir, and Crowder could slot in as a starter on a number of teams in the league -- teams where they wouldn't be expected to do much more than defend, rebound, hustle, keep the ball moving, cut to the rim, and hit open shots.
I'm less sure about Lee, Olynyk, or Sullinger starting, just because I think their defensive weaknesses make them harder to carry in a lineup.
Perhaps a better way to put it is that nobody on the Celtics would be a core piece (i.e. a central part of the game plan) on any of the better teams in the league.
I think IT could go to a number of teams and be a big boon to their second unit, but on a good team he wouldn't be a key part of the game plan. It's fair to wonder how happy IT would be on a team where he was "just" a bench scorer and not the primary scoring option anytime he hits the floor, as he is for the Celts.